We quickly lose sight of how exceptional the bizarre moments of the past six months have been. It would have seemed ludicrous one week ago that we’d be sitting here today holding an email in which Donald Trump Jr. cops to seeking out negative information about Hillary Clinton from someone he believed was a Russian government official. Yet here we are.

Trump’s base of support has already appeared to brush aside the obvious demonstration of a willingness to collude in the transfer of information that was “part of Russia and its government’s support for Mr. Trump,” as the first email to Trump Jr. read. President Trump once said that he could shoot someone dead in the middle of Fifth Avenue and not lose any support. That no longer seems much like hyperbole.

President Trump spoke at a news conference in Paris on July 13 and defended Donald Trump Jr.'s meeting with a Russian lawyer. (The Washington Post)

Still, others will note, it’s not as if Trump is popular. His approval rating remains mired in the low-40s, with most Americans viewing his job performance negatively. Doesn’t that alone mean that, if some other significant revelation occurs over the next seven days, Trump’s position must surely grow wobblier?

Nope. Despite a Democratic member of the House initiating the process to remove Trump from office, there’s almost no chance at all that the president would be impeached this year, no matter what happens.

Why? Politics. Impeachment takes the form of a trial, but it isn’t one. It’s a political vote by politicians, all of whom would like to themselves avoid the fate of being thrown out of office. And Trump’s political career both relied on and thrives because of the nature of the moment that he launched it.

Let’s go back to those approval ratings. Here are the average ratings by party for each day on which a poll was conducted for the first six months or so of Trump’s presidency (via Huffington Post Pollster).

There’s been a distinct downward trend, both among all voters and in Trump’s base, members of the Republican Party. But the drop-off hasn’t been all that steep; he’s polling about seven or eight points lower now than he did in January, with a similar decline among Republicans. It varies by pollster and methodology, as you might expect.

As we’ve noted before, though, the only number that really matters is that approval rating among Republicans, for reasons we’ll get into below. If your job depended largely on majority approval from a group of 10 of your peers, you probably wouldn’t start updating your résumé just because you went from having nine of them love you to only eight.

Let’s dive in a little by looking at the numbers from Gallup. The weekly average of approval ratings for Trump by party looks like this. In Gallup’s numbers, he’s down seven points from his January polling among all voters — and down only four with Republicans.

But there’s a critically important split in those Republican opinions. Conservative Republicans are much more likely to view Trump positively. With that group, he’s consistently been at around 90 percent approval.

Remember, we noted that impeachment is a political process. It requires having members of the House pass articles of impeachment that then go to the Senate where punishment is determined. And every single one of those 435 members of the House have to face their own constituents next year in an effort to keep their jobs. Most (but certainly not all) will face challengers from within their own parties who they’ll need to defeat in primaries in order to be on the ballot in November.

And that is why Trump isn’t going anywhere any time soon.

In 2014, Pew Research Center looked at the composition of the primary electorate. It found that in the 2010 and 2014 off-year elections, the people who came out to vote in the Republican primaries were much more conservative than Republican voters overall. In 2010, the voting pool was 12 points more likely to espouse consistent conservative views on policy issues than Republican Party voters overall. Three years ago, the voting pool was 11 points more conservative.

To break it down explicitly: Republicans control the House, so nothing’s passing there without their support. Republican House members are all up for reelection next year. To get on the ballot in November, they need to win their primaries. Their primary fights will be against other Republicans (in most states), and be determined by the most conservative voters in their party.

And those conservative Republicans have a 90 percent approval rating for President Trump, even after all of the things that have emerged over the last six months.

Those hoping for a Trump impeachment, then, might wonder what happens after the primaries. After all, it’s not a coincidence that Richard Nixon resigned in August of 1974, after his party’s primaries that year — and after a visit to his office from congressional leaders who warned that his support on Capitol Hill had collapsed. Part of the concern, clearly, was that Nixon’s unpopularity was going to lead to a bruising defeat for House Republicans that November.

That may be a concern for House Speaker Paul D. Ryan next year, too, but there are two big differences. First, Republicans have a very healthy margin in the House that would allow them to lose more than 20 seats while still maintaining a majority. Second, there are a lot fewer close House races now than there were then — a function of a lot of things including population sorting and gerrymandering.

In 1974, the winners of 90 House seats were settled by margins of 10 points or less (including the Republican minority leader in the House who’d met with Nixon). In 2016, it was a third of that.

In 2016, only 15 Republicans were elected with margins of under 10 points.

To put a fine point on it: Far fewer House Republicans are dependent on cobbling together support from voters outside of their party in order to win reelection. And since the most fervent supporters within their party stand strongly behind Trump, that may offer them all of the political cover they’d seek.

Theoretically, something else could emerge that would cause Trump’s support from those Republicans to crumble. But it’s very, very hard to imagine what that might be.